Hello Navaratan,
If you are not using the 
(BEGRU) field of MPts, then you have a better opportunity to use this field for filling with codes TCM1, TCM2, GEN1, GEN2 etc. Hope you have followed. And based on this you can retrieve the IMRG records to your report. This is an alternative method to the proposed MPt desciption change.
According to this Two measuring points will have the value TCM1 one daily MPt and the other hourly MPt.
I believe these things of MPts are better than your MDTXT idea. (You will be free from entering MDTXT everytime you create a measuring document)
Good luck
KJogeswaraRao